s
Russian Gemstones Encyclopedia

Vladimir Bukanov. Russian Gemstones Encyclopedia

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

OLIVINE, GROUP: OLIVINE (CHRYSOLITE), LIEBENBERGITE, TEPHROITE


OLIVINE group (Olivin—Olivine—ќливин) (Werner, A.G. 1790). The name reflects the common olive-green color of the magnesian variety. Peridote, from Old Fr. “peritot”, which, perhaps, leads its origin to the Arabic word “faridat” – precious stone. Fayalite (Gmelin, J.F. 1840), after its discovery locality, on the Fayal Is., Azores; although believed to occur in the local lavas, it was probably found in slag carried as ship ballast. Forsterite (Lévy, A. 1824), after A.J. Forster (1739-1806), an Engl. mineral collector and dealer; founder of the Heuland Cabinet. Chrysolite (Wallerius, J.G. 1747) from Gk. “chrysos” – gold and “lithos” – stone, after its color. Besides, here liebenbergite and tephroite will be described, which form an isomorphic row olivine group.

Composition & Properties. Silicate – (Mg,Fe)2[SiO4], from the subclass of orthosilicates, orthorhombic system. Hardness 6.5-7. Density 3.2-4.2. Glass luster. Fragile. Olivine itself performs an isomorphic row from ferrous fayalite to magnesian forsterite. Chrysolite is a name, accepted for the intermediate variety of this row. Since the 18th cent., in Russia chrysolite has been served as a synonym to noble olivine, but in the Western gemology it was used to call it peridote. Chrysolite usually is found as grained aggregates. Rarely short-columnar crystals not more than 20 cm. long is found. Transparent to translucent. Color is yellow-green, olive-green, dark green, brown. Color depends on the content of iron (Fe2+), less on the content of nickel and chromium, which give brightness to green color. The distribution of color can be uneven. Color of chrysolite from placers is usually less intensive. Such mineral inclusions are typical for chrysolite: diopside, magnetite, serpentine, micas, chalcopyrite, chromite and spinel. Inclusions of needles of chrysotile and ludwigite lead to the effect of cat’s-eye and asterism in the shape of six-radial and four-radial stars in cut star chrysolite. Chrysolite with opalescence has the trade name chrysopal. Annealing, as a result of the restoration annealing can weaken thick color of chrysolite.

Deposits. Chrysolite is usually of magmatic origin, but its best crystals are formed in the process of metasomatism, as a result of trans-crystallization of rock olivine under the action of hydrothermal solutions. Industrial deposits of chrysolite are in kimberlites, basalts, alkali basaltoids and ultra-rocks. In the process of their weathering rich placers appear. Forsterite is a mineral of magnesian skarns. Fayalite is found in cavity of volcanic bombs in lavas. In Russia, at the iron-ore Kovdor deposit, in the Murmansk Region, greenish-gray crystals of forsterite, up to 3.5 cm. were found. They were very crackled, had zone structure with the transfer into pale colored chrysolite to the center of a crystal. Cut gemstones were made from transparent parts of crystals. In 2001, in the South Urals, in the valley of the Bol’shaya Satka River, forsterite was found, which to arouse a great interest as a new gemstone. It’s small-grained and needle aggregates contain glassy phase of the same content. Its color is indigo-blue to violet. Needle elements produce the iridescence in cut stones. This new gemstone was suggested to call indigoforsterite. In 1962, in the northern part of the Krasnoyarsk Region, 160 km. to the south from Khatanga, the Kugda deposit of chrysolite was discovered. It is situated near the mouth of the Kotuykan River, a right tributary of the Khatanga River, in the massive of ultra-rocks; it is represented with olivine veins. In the weathering cover layer veins and country rock disintegrated. Chrysolite of gem-quality is found in veins as nests together with clinohumite, serpophite, perovskite and phlogopite. Length of olivine veins reach 300 m., size of nests is not more than 30 cm. in crosssection, and only rarely they form bulges up to 3.5 m. in size. Size of fragments of chrysolite crystals is from 3x5x5 up to 7x10x15 mm., the output of rough material for cutting in nests is not more than 3%. At the deposit the resources of rough crystals for cutting are evaluated. To the south from the Kugda deposit there is a locality of chrysolite Bor-Uryakh of the same type. In the Eastern Sayan Mts. there is the Khara-Nurskoye locality of chrysolite in the upper reaches of the Urik River; and in the Amur Region there is the Tokskoye placer-deposit. The latter one was discovered on the Nakit River, the right tributary of the Tok River, in the basin of the Zeya River, in 1981. It was formed as a result of destroying of olivine basalts, which contained olivine nodules up to 40 cm. in cross-section. Fragments of crystals, which are good for cut, are not more than 1.5 cm.; the output of chrysolite good for cut from rough crystals is not more than 65 gm./m3 . Chrysolite is characterized with intensive golden-green color of pure tones. Samples of chrysolite deposits in kimberlitic pipes are in the Rep. Sakha (Yakutia). So, the pipe Udachnaya-Vostochnaya is rich with chrysolites, its crystals maximum to 1.6 cm., were extracted there, and the content of rough crystals was 19 gm./m3 . In Tadzhikistan, at the noble spinel Kukh i Lal deposit, in crystal pocket with spinel and clinohumite they described transparent forsterite or white clinohumite (pamirite) in crystals up to 1.5 cm.

In Europe chrysolite is found in Spain – in Andalucía and on the Canary Iss., in alkali-basalts of the Lanzarote Is. In Germany – in the Eifel Mts., near Mayen, Rhineland-Palatinate. In Norway, forsterite crystals up to 25x15 cm. at the Modum deposit, near Bergen, were found; also in yellow serpentinite at Snarum. There is also brown because of biotite inclusions star chrysolite with asterism. Findings of chrysolite good for facet are known in Italy, where olivine nodules with transparent parts of chrysolite up to 5 cm. in size were found. In Egypt, the deposit of chrysolite in serpentinous peridotites of the St-John Is. (form. Zeberget) in the Red Sea has been known since ancient times. It had been exploited in 3,500 B.C. and was rediscovered in 1905. The biggest crystals from this deposit reach the size of 3.5-4.5 cm. rarely – up to 10 cm. In France, in the Museum École Nation., Paris, there is a crystal of chrysolite from the Zeberget Is., 4.5 cm. long; also in British Museum, London, the crystal 6.6x5.1x2.5 cm. is exhibited. In Kenya, large brown chrysolite crystals at the Emali deposit are extracted; in Tanzania – at the placers on the Umba River, and at the diamond pipe Mwadui. In Ethiopia, in the southern part of the country, in the Sïdamo Kifle Häger region, near Megä, gem-quality chrysolite, up to 2 cm. was found in olivine nodules among basalts, together with chrome-diopside and spinel. In South Africa, chrysolite from kimberlites in the diamond pipes De Beers and Kimberley was extracted.

In Myanmar (Burma), at the deposit of nickel-ores near Mogok chrysolite crystals, up to 50 gm. weights, and forsterite, up to 25 cm. in size, were found. There, at the Kyaukpon deposit, near P’ingaung, in the weathering layer of peridotites, the biggest in the world transparent crystals of chrysolite are extracted; cut stones up to 200 ct. were made from some of them. Sometimes, after cut they perform the effect of aventurescence. Also, there were findings of forsterite up to 6x3 cm., from which cut stones up to 65 ct. were made. At placers of Sri Lanka, Ratnapura region, almost colorless gem-quality chrysolite was found; and sometimes occurs crystals forsterite up to 30 cm. at Kolonne, near Embilipitiya. In the southern part of Vietnam, in weathered basalts of the Gia-Lai and Lam Dong Prov., a deposit of chrysolite is exploited. In China, similar the Zuanhua deposit was opened in 150 km. to the north-west from Beijing; Hebei Prov. in 1979; with crystals chrysolite up to 25 ct. Of the same type is the Shavaryn Tsaram deposit in Mongolia, where olivine bombs in basaltic breccias up to 1 m. in cross-section, filled with chrysolite, were found. In Pakistan, North-West Frontier Prov., at the border with the Indian state of Jammu and Kashmir (disputed area), not far from the Nanga Parbat Mt. (8,126 m.), forsterite crystals – Kashmirian peridote up to 20 cm. long at the Sumput deposit, Mänsehra Dist., are extracted. In Afghanistan a similar deposit in serpentinites near Kandagar is known, where yellowish-brown olivine of gem-quality – royal stone has been extracted.

In the U.S.A., in Arizona, there are large deposits of chrysolite in basalts: San Carlos and Bewell Park, and there placers as well, with crystal aggregates up to 20 cm., cross-section. Similar deposits are in the states of New Mexico, and Massachusetts. On the Hawaii Iss., in cavity of volcanic bombs in lavas they find transparent crystals of fayalite or hawaiite. In California at the Crestmore quarry chrysolite after cutting has chatoyancyCalifornian tiger’s-eye. It is extracted there from weathered kimberlites, basalts and olivine bombs in separate parts up to 30 cm. in crosssection. Rough material in fragments up to 2 cm. gives a possibility to produce cut stones not more than 5 ct., maximum up to 35 ct. Of the same type is the Chivera mine one of the largest in the world deposits of gem-quality chrysolite in the northern part of Mexico, Chihuahua. Chrysolite from this deposit is light green and brown; they make cut stones up to 20 ct. from it. In the Durango State, transparent bright green forsterite crystals up to 2 cm. at the Mapimi deposit, near Suppat, are found. Less significant deposits of chrysolite are in Brazil, in Minas Gerais, and in New Caledonia.

Ornamental rocks. In the southern part of Germany, in the Neurode region, Hessen, there is known an ornamental rock of significantly labradorite content – forellenstein or trout stone. It is olivine gabbro with the replacement of olivine with serpentine. The rock is massive, white-gray in color with bluish tone and black spots of olivine. The same rock is found in the Armenia, near Sevan Lake. It accepts mirror polishing and it is good for large stone-cut produce. In Greece, in the Western Macedonia, fine-grained light green olivine rock is extracted as an ornamental stone – it is olivine jade with inclusions of magnetite. Besides, gem-quality chrysolite is found in ironstone meteorites, which fall in East Siberia and the Argentina.

Synonyms. Fayalite – Ferrous chrysolite | Iron glass | Neochrysolite | Talasskite, after the discovery location in Talasskaya valley, Kyrgyzstan.

Forsterite – Boltonite, after the discovery location near Bolton, Massachusetts, the U.S.A. | Common chrysolite. | Volcanic chrysolite | White chrysolite | White clinohumite | Bastard emerald | ~ olivine: magnesia ~, prismatic ~, star ~, white ~ | Pamirite, after the discovery location at the Pamirs Mts., Tadzhikistan.

Chrysolite – Olivin basaltine | Bostonite | Chrysoberyllus, by Agricola | ~ chrysolite: Arabian ~, by Pliny the Elder; Arizona ~, after the discovery location in Arizona, the U.S.A.; brown ~, Ceylon ~, Egyptian ~, after the discovery location in the Saint-John Island in the Red Sea, Egypt; Hawaiian ~, after the discovery location near Heelo, on the Hawaii Iss., the U.S.A.; Indian ~, by Pliny the Elder; Levantian ~, meteoric ~, Tabaran ~, from Asia Minor, by Pliny the Elder. | Hawaiian diamond | Dostocan, Old Russ. | Evening emerald | False emerald | Night emerald | Glinkite, from Russ. general V.A. Glinka, from the region of Itkul’ Lake, the South Urals, Russia | Hawaiite, after the discovery location on the Hawaii Iss. | Hyalosiderite from Gk. “hyalos” – glass and “sideros” – iron, after the content | Jacinph, Old Russ. | Kraselit, local Ural., Russia | Andalusian olivine, after the discovery location in Andalucía, Spain | Precious olivine | Spanish olivine | Olivinoid | Arizona peridote | Ceylon peridote | Bottle stone | Gold stone | Royal stone | Topatius, by Agricola | Zaberzat, after the discovery location on the Zeberget Is., Egypt.

Cut Gems. In the ancient times chrysolites were used as a name for many golden-yellow stones: beryl, topaz, chrysoberyl, citrine and others. Jews knew it as tarshish – the tenth stone on the breastplate of the high priest. In Ancient Rome it was not differed from emerald. It is clear from the legendary “Neron’s Emerald”, which is kept in the treasury of Vatican, – really it is chrysolite. In Egypt, in the Museum Egyptian Antiques, Cairo, chrysolite beads of the 4th cent. B.C. is kept, as well as an olivine scarab (1580-1350 B.C.). In the Middle Ages, in the epoch of the Crusades, chrysolite was taken to Europe and used for the decoration of church objects. That time it was called crusaders emerald. In the icon-frame of the icon by Andrey Rubliov “Holy Trinity” from the Trinity-Sergio’s Lavra there is also chrysolite under the name of zaberzat. In the collection of gems in the State Hermitage, SPb. there are some cameos on chrysolite, including one, 1.6x1.4 cm. in size, from Germany, the 17th cent., with the depiction of a bust of a Gk. philosopher. In the epoch of the high baroque, chrysolite was the most popular in jewelry. In the early of the 19th cent., it was in fashion in Paris; a new wave of interest to chrysolite came in the early 20th cent. – it was a period of the “green fashion” of the Art Nouveau.

Unique cut stones: In processing of chrysolite usually step or diamond patterns of faceting are used. In jewelries the best for it is a gold frame. In the U.S.A., in the Smiths. Inst., Wash., and the biggest cut chrysolites are kept: from the Zeberget Is. 310 ct., from Myanmar (Burma), an oval, dark green one, 289 ct. The biggest of the cut chrysolites from Myanmar had the weight of 319 ct. Aperfect in purity olive-green cut chrysolite is among the seven historical stones of the D.F.R., Moscow. It has an ancient combined faceting, the weight of 192.6 ct. and the size of 5.2x3.5x1.05 cm. In the same place, a chrysolite set of the 18th cent. is exhibited; it consists of an openworked band with a large chrysolite in the center and chrysolite earrings with large stones – briolets. In the Geol. Museum, London, a square step-cut chrysolite is exhibited; its weight is 146.17 ct. In Canada, in the Royal Ontario Museum, Toronto, there are some stones from Myanmar: 108, 81.7 and 83.3 ct. In Germany, in the Museum of Idar-Oberstein, there is an oval facet stone, 80 ct. In Austria, in the Kunst. Hist. Museum, Vienna., there are two such stones, the biggest one is 53 ct. In the U.S.A., in the Smiths. Inst., Wash., a unique diamond necklace (designed by Salvador Dalí) with 184 chrysolites is kept.

Legends. The Church dedicated chrysolite to the apostle Mathews. In the epoch of the high baroque olivine was called a stone of beloved; they supposed it had a magical force to protect from heart diseases and unlucky cases. In the East they thought it helped to understand languages of birds and animals and to avoid nightmares. Astrologers keep it as a lucky stone for those, who were born under the signs of Leo, Virgo and Libra. In Egypt, chrysolite is a national symbol of country.

Synthesis. Synthetic forsterite with obvious pleochroism from violet to dark blue and up to purple is used for the imitation of tanzanite. It is known under the trade name tanzanion, their synthetic crystal grows up recently by Czochralski’s method in weight up to 250 carat. Surely, it is an analogue of natural indigo-forsterite from the South Urals.

Similar Gemstones & Imitations. Chrysolite looks like beryl, vesuvianite, demantoid, diopside, moldavites, chrysoberyl, prehnite, sinhalite and tourmaline. As an imitation of chrysolite colored glass, doublets garnet—glass, triplets from synthetic spinel with the inner layer of enamel, and also synthetic: spinel, corundum and phianite of the good color are used.

Liebenbergite (Liebenbergit—Liebenbergite—Ћибенбергит) (De Waal, S.A. & Calk, L.C. 1973), named after W.R. Liebenberg, Deputy Director-General, National Inst. for Metallurgy, South Africa. Composition – Ni2[SiO4], rare silicate, orthorhombic system. Hardness 6. Density 4.6. It is found in South Africa as small yellowish-green crystals in nickel-containing serpentinite in the region of Barberton. The commercial interest is connected with its synthetic analogue – synthetic liebenbergite. It is received from the solution in fused material on the base of natural olivine. In the U.S.A., the firm “Union Carbide” produces another analogue of liebenbergite – synthetic nickeliferous olivine for jewelry purposes. It is received with the method of melting in flame and with the method of pulling from the fused material. Besides, synthetic vanadium containing olivine of dark blue color is received with the same purpose.

Tephroite (Tephroit—Téphroïte—“ефроит) (Breithaupt, 1823), from Gk. “tephros”, ash-colored, alluding to the usual color of the mineral. Composition – Mn2[SiO4], rare silicate, orthorhombic system. Hardness 5.5-6. Density 3.7-4.1. Diamond luster, to greasy one. Cleavage in one direction. It is found usually in complete masses, it is very rare in short prismatic crystals. Its color is olive green, bluish green, flesh red and reddish gray. In Russia it is found at manganese deposits of the Polar and South Urals, in the Primorskiy Region – at the Temnogorskoye tin deposit and in rhodonite rock on the Shantarskie Iss. In Central Kazakhstan tephroite at the mines Karazhal and Zhumart is found; in Kyrgyzstan – at the Trudovoye deposit, near Issyk-Kul’ Lake. In Sweden, tephroite in columnar crystals exist in the ores of the deposits at the Långban and at Harstigen, near Pajsberg, Varmland region. In Italy, at the Val Gravelia deposit, Liguria, is known. In South Africa, as gray-violet crystals tephroite up to 2 cm. at the mines N’Chwaning II and Wessels, Northern Cape Prov., was mined. In Australia, it good crystals at Broken Hill, New South Wales, is known. In the U.S.A., massive accumulations of tephroite at the Franklin and at Sterling Hill manganese deposits, New Jersey, were found; also and others states. For jewelry purposes synthetic tephroite is produced, which has alexandrite effect.

Search